PRODUCTION OF SEAMLESS HOT-WORKED MACHINED 610×36, 53×3100-3300 mm FOR REFINERY COMMUNICATIONS WITH STRINGENT REQUIREMENTS TO GEOMETRICAL SIZES Russian patent published in 2015 - IPC B21B21/00 B21B21/04 

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling. Ingots are forged to 630×100×1630±50 mm pieces. Through central 100±5 mm diameter bore is drilled therein. Billets are heated to ductility temperature and pierced at helical rolling mill at 350 mm diameter mandrel with increase in diameter of 1.6-1.8% to 640×365ID×2150-2280 mm sleeves with rolling out of µ=1.35-1.40. Sleeves after piercing are cooled to ambient temperature with the turn through 180 degrees in 20-30 minutes. Sleeves are heated to ductility temperature. Sleeves pierced-rolled at helical rolling mill at 485 mm diameter mandrel with increase in diameter of not over 1.6% to 650×500ID×3340-3540 mm sleeves with rolling out of µ=1.55-1.56. Rerolled sleeves-billets are cooled to ambient temperature with the turn through 180 degrees in 15-20 minutes. Sinks are thermally processed and cut off from front and rear ends. Said sleeves-billets are bored and turned to surface finish Rz not over 40 mcm.

EFFECT: higher surface quality and precision.

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